I also like the digital twin concept as it applies to sci-fi. Sometimes I daydream our universe is a digital twin built by an advanced civilization meant to simulate the universe's history looking for clues as to what lead to a calamity that they're trying to undo. Random thought :)

Interesting, I have a couple of questions:

- How do model random variables with high variance like occupancy or equipment use? Are you using sensor/monitoring equipment or just trying to model it as best as you can?

- Did you guys use the initial energy model (built by by the design/consultant team) or do you guys build your model from scratch?

- What energy simulation engine do you guys use? I'm just curious if there's any big advantage between the engines for digital twin applications.

- We use a ton of empirical time series data from the building to calibrate the model.

- There's almost never a model. We build it from scratch in every case.

- We have a highly customized fork of EnergyPlus. They are all difficult to use in our experience, but EnergyPlus allows us to get the detail required for our needs.

Fascinating. Would love to see a "digital energy twin" product for residential properties.

Would love to hear what you're thinking! We've prioritized commercial office as it's great bang-for-buck for our business, but we'd love to expand to other verticals in the future.

Essentially, provide a way to build a digital "twin" version of my house, and get advice about improving heating/cooling efficiency.

Can/does your system simulate the quality of the air as well? In particular particulate matter and CO2 levels.

We've given this a lot of attention in the age of Covid, as you might imagine. Many modern HVAC control systems include CO₂ sensors in the return air streams to make sure they're bringing in enough outdoor air to meet indoor air quality standards, and that's fairly easy to simulate. Particulate counts are trickier, and may be better estimated using out-of-simulation engineering calculations based on the type of filtration in place.

Interesting, mind if I shoot you an email? My family has a business in this space (residential side) and I'd love to chat more.

Sure! brian at bractlet dot com